The invention relates to a core holder for a winder for the centerless winding of webs, having a motor-driven spindle for the axial displacement of the core holder which is rotatably mounted on a sliding shaft mounted in a quill, a travel limiting means being provided to limit the axial movement of the core holder.
In the centerless winding of webs in a winding machine in which the roll is cradled between two supporting cylinders, the roll is held axially by the core holders set into the opposite ends of the roll. To change rolls it is necessary that at least one of the core holders be able to be axially shifted over a distance of, for example, 50 mm. For this displacement, a motor-driven spindle is provided, which engages the sliding shaft of a core holder. Several means are known for limiting the length of axial travel. In a first known travel limiting means a counter is provided which receives counting pulses produced by the rotation of the spindle and operates the drive motor according to the counting pulses received. A second, purely mechanical travel limiting means consists of two abutments engaging the sliding shaft.
In the event that the winder has to be reset for a smaller size, i.e., for a shorter distance between the core holders, it is necessary to extend the core holder on the sliding shaft beyond the position set by the travel limiting means. To make this possible, the electrical control means in the case of the first travel limiting means is so constructed that the stop pulse given to the motor by the counter when the one position is reached can be inactivated. The numerical value set at the counter for limiting the movement is preserved, however, so that, when the new core holder position is reached, the control means can act with the counter as a travel limiting means the same as it did at the former position. The changeover to another size in the case of the second, purely mechanical travel limiting means is, however, substantially more complicated. In this case it is necessary to loosen from the sliding shaft a pawl which cooperates with the abutments, so that it can be displaced axially on the sliding shaft. Not until the core holder has reached its new position can the pawl be locked axially again on the sliding shaft.